AWWA WQTC58977

Triclosan, 5-chloro-2-(2,4 dichlorophenoxy)phenol, is an anti-microbial agent used in many pharmaceutical and personal care products (PPCPs) such as toothpastes, soaps, and detergents. Because of its widespread use, significant amounts of triclosan are introduced to wastewater treatment systems. The removal of triclosan during wastewater treatment is dependent on the type of secondary treatment employed. Presumably due to its incomplete removal during wastewater treatment, triclosan has been detected in 58% of the U.S. waterways examined in a recent US Geological Survey study. As with many other PPCPs, triclosan is a phenolic compound. Recent studies have demonstrated that phenols react with free chlorine to form disinfection byproducts such as Trihalomethanes. While studies in the past have examined triclosan-free chlorine interactions, the kinetics of these reactions have not been investigated. Monochloramine is also commonly used for drinking water disinfection. However, the reactions and kinetics of monochloramine with triclosan have not previously been reported in the literature. The objective of this study was to evaluate the kinetics and the reaction pathway of the triclosan/free chlorine and triclosan/monochloramine reactions. A mechanism was hypothesized to explain the pH dependency of the triclosan/free chlorine reactions. Products of the reactions were identified and monitored with reaction time. Includes 8 references, figures.